Self-locking threaded device



Jan. 16, 1945.

H. R. HARDING .SELF-LOCKING THREADED DEVICE 4 Sheets-Sheet 1 Filed March 26, 1943 Inn-12 I Jan. 16, 1945. R R m 2,367,213

SELF-LOCKING THREA E H. 3. HARDING SELF-LOCKING THREADED DEVICE Jan. 16 1945.

" 4 Sheets-Sheet 3 Filed March 26, 1943 Jan. 15;"1945. H. R. HARDING SELF-LOCKING THREADED DEVICE 4 Sheets-She et 4 .1. Hal-Mi,

Filed March 26 1943 Jame/Mom.

threaded devices.

Patented Jan. 16, 1945 s PATENT OFFICE SELF-LOCKING THREADED DEVICE Hiram R. Harding, Baltimore, Md., assignor.to

. Crown Cork & Seal Company,

tion of New York Inc., a corpora- Application March 26, 1943, Serial No. 480,684

22 Claims.

The present invention relates to self-locking An important object of theinvention is to provide a self-locking threaded element of such construction that when it is used with a companion threaded element, neither element can move with respect to the other due to'vibration. 1 Self-locking threaded elements or looking devices for threaded elements-now ordinarily used are of several types. The type most widely used includes a separate key or. some similar independently operated member to hold the threaded elements in locked position. An objection to arrangements of this type is that if the key or other locking device is broken, the threaded elements cannot be unlocked. Also, if the locking device is of such design that it is entirely separable from the threaded elements, it may belost before use so that the threaded elements cannot be locked.

' Some designs of locking devices of the type just discussed require special tools for the fitting and releasing of the locking members. If the special tool is not at hand when unlockingis to be performed, it may be impossible to release the threaded elements.

An object of the present invention is to provide aself-locking threaded device which includes no independently operable locking device and, there- 'fore, includes no parts which can be readily broken or lost. I I

A further object of the invention is to provide a self-locking threaded element which is entirely operable by the usual tools required to thread elements with respectto each other.

Another object of the present invention is to provide a self-locking threaded element including a locking device which is permanently applied to the threaded element during manufacture and cannot become separated therefrom.

Another type of locking device in wide use involves a separate washer which exerts friction between two threaded elements. These devices may deteriorate under certain conditions, particularly if they are of compressible material.

I Another object of the invention is to provide a self-locking threaded element wherein the looking device forms part of the threaded element and is formed entirely of metal.

.Another object of the invention is to provide a self-locking threaded element of such design that ,the device which gives it a locking characteristic is extremely strong and cannot become broken during use. g

A still further object is to providea self-locking threaded element oi such construction that the locking device will be entirely enclosed b the threaded elements which it secures together. Hence, the locking device cannot be tampered with.

-In one form of the present invention, the elements can be unthreaded upon the application of suflicient force thereto. However, despite the strong locking action, no threads'wi1l be marred during unthreading. Another form of the invention is of such construction that the elements cannot be unthreaded.

Other objects and advantages of the invention wi1l be apparent from the following specification and drawings wherein: Figure 1 is an elevation of a cap sdFw constructed in accordance with the present invention;

Figure 2 is a view showing the cap screw in side elevation and illustrating a comp-anion threaded element in axial section;

Figure 2a is a transverse section on the line 2 a-2a of Figure 2;

Figure 3 is a view similar to Figure 2, but showing the cap screw fully threaded into the com-.

panion threaded element;

Figure 3a is a transverse section 'on the line 30-31; of Figure 3; v

' Figure 4 is a view similar to Figure 2, but showing the action of the invention upon unthreading the line 6-6 of Figure '7 is a view of the cap screw viewed from I the right of Figure 1;

Figure 8. shows the cap screw with the floating thread member removed; I Figure 9 is a side elevation of the floating thread member;

I Figure 10 is a cross-sectional view through one arm of the member of Figure 9;

Figure 11 is a plan view of the member shown;

in Figure 9;

Figure 12 is a view of the floating thread member viewed from the top of Figure 11;

Figure 13 shows a modified form of the invention threaded into a companion threaded element;

Figure 14 is a plan view of the floating thread member used in the figure 13 form;

Figure 15 is a showing of the floating thread member of Figure 14 as viewed from the top of the latter figure.

Figure 16 is a side elevation of the end of a cap screw of a second modified form;

Figure 17 shows the Figure 16 cap screw provided with a floating thread member and par tially threaded into a companion threaded member;

Figure 18 shows the device of Figure 1'? further threaded into a companion threaded membe Figure 19 is a transverse view on the line l9l 9 of Figure 17;

' Figure 20 is a development of the Figure 18 structure; and

Figure 21 is a side elevation of the floating threaded member illustrated in Figures 17 to 20.

Referring to Figures 1 to 12, the numeral I designates a cap screw constructed in accordance with the present invention, the cap screw being provided with a U. S. Standard thread indicated at 2. As best shown in Figure 8, the outer or leading end of the cap screw has a portion of the threads removed therefrom as indicated at 3, with the result that the thread of the cap screw begins at the point 4 which is spaced from the point at which the thread would normally begin on such a cap screw. The length of thread beginning at point 4 is of very short extent and terminates at an axially extending groove 6. Beyond groove 6, one helix of the thread 2 is entirely omitted and, instead, a helical groove l is formed in the cap screw, groove 1 extending substantially 360 to enter the opposite side of the axially extending groove 6.

As is best shown in Figure 2a, the helical groove 1 and the axial groove 6 are of the same depth and, as illustrated in Figure 8, they extend below the root diameter 9 of the threads 2 a distance substantially corresponding to the height of the threads 2. The side walls and l l of the a'xially extending groove 6 lie in planes parallel to a diameter of the cap screw and everypoint of each side wall l2 and I3 of the helical groove 1 lies in a radius of the cap screw. The bottom wall I4 of the axially extending groove 8 may 'be either flat or rounded in a plane transverse of the axis of the cap screw as shown in Figure 7 and its inner end l5 may also be rounded as shown in Figure 8. The bottom wall l6. of the helical groove 1 is concentric with the axis of the cap screw, except as hereinafter described.

It will be observed that the wall Ill of axial groove 6 comprises the leading edge wall of that groove in that wall ill will be leading during threading of the cap screw with respect to a companionthreaded member. The wall ll comprises its trailing wall. The helical groove 1 must be regarded as extending into axial groove 6 in that the end of thread 5 on leading wall ill of the axial groove forms. an abutment at the leading end of the helical groove. Also, the end 3| of the thread 2 beginning at the wall ll of axial groove 6 forms the trailing end of helical groove V1 in that it forms an abutment at the trailing end of the helical groove.

As best indicated in Figures 2a and 7, the helical groove 1 includes a restriction in the form of a radial projection'or enlargement on its bottom wall IS. The restriction 28 includes a surface 2| concentric with the axis of the cap screw extend approximately 25. An incline 22 also forming part of the restriction joins the bottom or inner wall It of helical groove 7 to the surface 2| of the restriction. Inclined surface 22 is preferably formed by a radius based outside the bolt so that the incline will be a concave curve. It will be noted that incline 22 forms the trailing side of restriction 2D. screw, the length of the incline 22 would be approximately 25-of the circumference of the cap screw. The leading edge of the restriction 20 is at the axially extending groove 6.

As best shown in Figure 6, restriction 20 is of such height that it is closer to the axis of the screw than the root diameter 9 of the threads 2. It will also be noted from Figure 6 that the unthreaded portion 3 of the screw is of 'the same diameter as the root of the threads 2.

A helical' band 25 shown in. detail in Figures 9 to 12 is fitted in the helical groove 1. As illustrated in Figure 11, the band 25 extends for approximately 335 and includes a fiat inner surface 26, and relatively short side walls 21 (see Fig. 10). Outwardly of the side walls 21, the band 25 is provided with a thread 23 of the same cross-sectional conformation as the threads 2 of the cap screw l. While member 25 is of generally helical form, it is not of uniform diameter. For example, as clearly indicated in Figure 1i, one end 29 is bent or deflected inwardly from a helix so that the innermost point on this portion is closer to the diametrically opposed point on surface 25 than is the case with anyother two diametrically opposed points on the inner surface 26.

The member 25 is formed of spring steel to be bodily resilient though it has suflicient rigidity to exert strong pressure against any effort to bend it inwardly from the normal form illustrated in Figure 11 and, when bent inwardly, will exert considerable force outwardly.

Figures 2 and 2a as well as Figure 7 show the band 25 fitted in the helical groove 1 of the cap screw l and it will be noted that the bent-in end 29 is adjacent the restriction 20 and thereby forms the leading end of the band while the opposite end 30 forms its trailing end. The diameter of the inner surface 26 of the member 25 is greater at all points than any diameter of the groove 1, with the result that member 25 will have movement diametrically of the groove and, when not within a companion threaded element, may move lengthwise or circumferentially of the groove. Because of this, the member 25-can be regarded as a floating thread. With regard to circumferential movement of member 25 in the groove'l, it will be clear-that, with reference to Figure 2a, mean only move clockwise to such extent that its trailing end 38 will abut against the leading end 3| of the threads 2 of the cap screw. When moved in the opposite direction, the leading or bent end 29 of member 25 will come into abutment with the short length of thread 5 after passing over the restriction 20.

It will be noted that when the cap screw l is free of any companion threaded element, the leading end or bent-in nose 29 of member 25 may be at any point on cap screw l between the position shown in Figure 2a and the leading wall It) of axial groove 6. In other words, because the member 25 is normally circumferentially free in the helical groove 1, it may turn with respect to the cap screw to occupy any position between these points.

For the purpose of setting forth the detailed In a .75" cap.

extending substantially 225 from its trailing end 30, and generally indicated by the arc F in Fig-- um 11, is formed concentric with the axis of the form of a typical self-locking element of the present invention as shown in Figures 1 to 12,.it may be pointed out that a .75" U. 'S.. Standard cap screw constructed in accordance with the present invention will have the base wall l6 of its helical groove 1 formed one. radius of .249" while the surface 2| of restriction Will be formed on a radius of .288". In accordance with the standard practice, the diameter of the screw at the root 9 of the threads would be .62".

It is to be noted that a .75." U. s. Standard coarse thread cap screw designed to have a No. 2 fit with a female element is finished to make the minimum outside diameter of its threads ".737" The-female or companion element to be used-with such a. screw would havethe maximum base di-'' ameter of its threads .750". In other words, with a No. 2 fit, such companionelements would have a diametrical play of .013".

The member to be usedwith a .75 U. S.

' Standard screw such as indicated by the numeral in the end to the diametrically opposite point,

is .7618"; Obviously, any outside diameter measured across any portion of arc F would also be 3618", l i Y Within arc G, which extends for 55 from arc F, the outside diameter of member 25 is formed on a radius of .364" which originates at a point Ion radial line F offset from thepointat which the radius of arc F originates. As a result any outside diameter extending through arc G would range downwardly from .7618" '(at F) to slightly less than .745". For example, the outside diameter along line D-D iii-Figure l1 would'approximate this latter measurement, whichis less than the .750" base diameter of the female threads and only slightly oversize with respect to the outside diameter of the threads. of cap screw 1. From 'radialline G, which indicates one end of arc G, the outside diameter is formed on a 1126'" radiusoriginating on line G, with the result that this portion isbent inwardly much more sharply. than the portion within arc G. .The inside clearance on line C-C passing through end 29 is .540", so that the minimum diameter is at this point.

helix and is oversize with respect to the threads of screw l. The remainder of member 25, extending-substantially 90 from its leading end 29, is formed eccentrically with respect to the axis of the helix and, throughout a substantial portion of its length, is of less radius than the outside diameterof screw l.

' In view of the above, the member 25 may be described as a distorted helix, or a helix having one-half its length bent slightly inwardly, with a sharp inward bend immediately adjacent its leadits leading end 29.

' engaged ing end. If the bent-in nose 29 is left out of consideration, member 25 may be described as a helix flattened on a diameter such as line D-D which extends through a point approximately 45 from It will be understood that the discussion of a .75" cap screw of the present invention contained herein is merely to disclose the dimensions used in an element of a given size, and that the invention is applicable to threaded elements of all sizes.

Figures 2 and 2a show the threaded element i of the-present invention being intially threaded into a machine body or base provided with U. S.

Standard threads 36. As illustrated in Figure 2a, prior to the time that the member 25'is entirely with the threads 36, its trailingportion, i. e., its portion adjacent the end 30, will occupy the expanded position shown in dotted lines at r the left of Figure Za'because of the fact that member 25 is oversized with respect to the threads 2 and 36 along its radii defining this portion. However, the resiliency of member 25 enables it to conform to the threads 36 when it is entirely engaged with these threads under application of sufficient force to the wrench being used. As soonas the leading end 29 of member 25 contacts with the threads 36, the member 25 will move backwardly in groove 1 to the position shown in-Figures 2 and 2a. This movement is due to the fact that if any portion of the nose29 is directly bearing on restriction 20 or is in ad-- vance of that restriction, the member 25 will project beyond the threads 2 at this point and,therefore, will be forced backwardly. When threading of cap screw l into a companion threaded member is started, the short thread 5 will serve to initially guide the two threaded elements to proper I I relation.

Because of the changes in radii at the lines F and G, these lines, in effect, comprise bending points of the member 25.

From the above, and from Figure 11, zft will be I noted that the smallest diameter of the member 25 is along a line extending through its leading endor nose 29 and that the portion within arc I Stated another. way, the portion. of '25 Because member 25 is oversize with respect to threads 2' and 36 on its radii within the arc F in Fig. 11, member 25 will exert considerable force against the threads 36 as soon as its full length is engaged with those threads. However, it will be 'noted from Figure 2a that the outer surface of member 25 adjacent its leading end 26 will not be closely engaged with the threads 36. This will permit this portion to move outwardly under the conditions hereinafter referred to.

, While'the member 25 will exert a considerable drag upon the threads 36 because of its tendency to expand to its normal condition shown in Figure 11, rotation of cap screw I can be accomplished by application of sufilcient force to the wrench used. Since the trailing end 30 of member 25 will be in abutment with the leading end 3! of thread 2 during'the threading movement described above, member 25 must necessarily 1'0- tate with screw l, despite the drag which the member is exerting on the threads 36 during threadinam a same relative position on the cap screw. .Inthis position, normal vibration cannot loosen. screw .1 because .unthreading movement, that is, movement in thedirection of the arrow E in Figure 3a,

will require thatthe trailingsurface '22of restriction 20 must move beneath the nose 29 of; member. 25. As is clear from the above, the strong force exerted outwardly against the threads=-36 by member 25 will prevent the latter fromhaving unthreading movement along the threads.

Hence, if screw I turns in the direction of thearrow E, it will turn relative to member 25. In. other words,.vibration cannot cause member 251301411111 with element I in an unthreading direction. In

fact, member 25 and element I can only turn together in an unthreading direction under the conditions described below and involving the ap- 'plication of extremely strong turning force to the element I,

If it is desired to remove the cap screw 1 from the element 35, a wrench of the usual form and size is applied to the cap screw and, upon the application of strong force to. the wrench, the cap screw may be reversely rotated in the direction of the arrow E of Figure 3a. The operation of the member 25 under these conditions is as follows: Because of its bodily resiliency and tendency to expand so that the greater portion of its length will be of larger outsidejradius thanthe diameter of the threads 38- of companion element 35, member 25 will be prevented from rotating in the element 35. However, with the proper force applied, the member 25 will bend adjacent its nose portion 29 so that the incline 22 of restriction 2c may move beneath nose .29

until the nose finally bears upon the surface 2!.

When the nose bear upon surface 2!, the cap screw can then be turned to move the nose off restriction 20 so that it will assume the position with respect to the cap screw indicated in Figures 5 and 5a. In this position the nose will lie in the axial groove 5 and will be in abutment with wall I!) of that groove so that the member 25 must then rotate with element I. While the oversize dimensions and resiliency of member 25 will still cause it to exert a strong drag against the threads 39 during rotation of the cap screw in the direc-.

tion of the arrow; E of Figure 3a, the, cap screw can be unthreaded with the application of proper force to the usual wrench.

Figure 11 indicates that with a .75" screw I,

the distance from the center to the closest inside point on end or nose 29 is .249". On the other hand, as stated above, surface .ll is-formed on a radius of .288". Hence, it will be clear that the member 25 must bend in the portion of its length between nose 29 and a point approximately 90 therefrom in order to permit nose 29 to move upon the surface 2i. As indicated above, the member 25 would be of such rigidity that considerably more force than could be gene-rated by vibration would be necessary to cause such bending.

In the form of the invention disclosed in Figures 13 to 15, the cap screw I, including the helical groove 1 and axial groove 6, are of a form identical with that disclosed in Figures 1 to .12. 1

However, the member 25a of Figures 13 to 15 differs from the member in that it is laterally offset. The expression laterally offset is used toindicatethat certain portions ,of, member 25a are offset along lines parallel to the axis of.v the member as clearly shown in-the three figures under discussion wherein member 2 5a isoffset inthe manner, described below.

. Referring to-Figure 15, it willbe noted that the member'25'a is provided with two offsets .60 and .62 which are substantially diametrically opposite.

.set adjacent, thev leading end SI is bent in such manner that itsconvex Wall is" faced toward the leading end of screw I. Thus, the convex Wall of offset 60 is faced toward a companion threaded elementsuch as 35. It, therefore, results that the convex wall of the other offset 62 is faced toward the headed or .trailingend of screw I.

It. is found that by having the convexwall of offset 60 faced toward the leading end of screw .I, an element I provided with an offset member 25a can be more readily initially threaded into a companion threaded element than is the case if the concave faceof offset 60 is faced in that direction. The .reasons for thisv are as follows: When the screw I has been threaded into element 35 only sufficiently to have the short length of thread 53nd the nose portion 6| of element 25a engaged by the threads 36, the pressure. naturally exerted by the operator in the direction of the arrow H of Figure 13 will cause element25ct to move or swing in the helical groove 1 in the direction of the arrow H of Figure 13. This is because of the fact that while member-25a for a .75" cap screw has an axial dimension of .08775", helical groove 1 may have an axial dimension or .width of .091". By having the hump of the offset 60 on the forward side of element 25a, the hump .is in. a position to take advantage of the space thus provided on the forward side of element 25!. Therefore, as the rotation of element I continues the offset 60 smoothly moves into engagement r with'the threads 36.

If the offset 60 were on the rearward side of 'element25a, theIatter'might pivot on the offset to cause its leading end GI to swingto the left in Figure 13 'so as not to track in the helix ofthread' 36 already engaged by the short length of thread 5.

Member 25a is of spring steel just as is the case with element 25 and, for a .75 cap screw, has allof 'the characteristics and dimensions set forth above in connection with theelement25 except for the offsets 60 and 62. The offsets extend axially sufficiently far to take up axial play between element I andelement 35, and also 'extend axially a very slight distance suflicient to cause the offsets to exert spring pressure on the threads 36 in an axial direction. This exertion of spring pressure in an axial direction, plus the radial spring pressure described above in connection with the member 25, causes an increased frictional elfect which further binds the'elements l and35 together. Engagement of'element 25a with the threads 36 maycause theoffsets to be slightly flattened against the resilient action ofthe offsets.

By having'the offsets 60 and 62 face in opposite directionsand by positioning them at substantially diametrically opposite portions of member 25d, screw I is held inaxial alignment with the threadedelement 35. More'particu larly,..if,.both:ofl'sets. faced in the slime direction,

16 .to 21, initial threading contact of the with the threads 82 screw I would have a component acting thereon to slightly tiltit in the element 35 and might have tilting play. By having the, elements face in opposite directions and positioned diametrically opposite, direction of the arrow Hf of Figure 13 while offset 62 exerts a force in the direction of the arrow H. These forces naturally balance to entirely take up all axial play. 6

Referring to Figures 16 to 21, the cap screw 'IIlillustrated therein is provided with threads II and a helical groove 12 which, throughout the major portion of its length, has the same characteristics as the helical groove 1 of Figures 1 to 15. However, the short length of lead the offset 60 exerts a force in the v thread 13 of the cap screw 10 has its trailing portion 14 downwardly inclined, or inclined to a point closer to the axis of the cap screw. It will be observed from Figure 16 that the inclination 14 is obtained by removing the trailing portion of thread 13 along a flat spiral. However, the portion 14 is not so deeply spiralled that it will merge with the base I5 of groove 12.. Instead, a concave shoulder .16 is formed at the trailing end of the incline 14 and which shoulder terminates at the base '15.

The floating thread element I8 used with the form of the invention under discussion is identical with that disclosed in Figures 1 to 12 except that its nose portion 19 is bevelled on its inner surface 80 as shown in Figures 19 and to coact with the surface 14. In addition, the side surfaces of the side thereof so that the nose terminatesin a point or wedge when viewed in elevation as is the case in Figures 17 and 18.

In the use or the structure disclosed in Figures floating element .18 with the threads 82 of a companion threaded member 83 will cause the member 18 to move lengthwise or circumferentially of the helical groove I2 until its trailing end 84 comes in contact with the abutment 85 provided at the trailing end of the groove 12. of the floating thread member, the nose portion 19 will occupy a position uponthe incline I4 somewhat as shown in solid lines inFigure l9 and as indicated in Figure 18. With the floating member in this position, the cap screw can be threaded forwardly into the element 83 by the application of sufficient force to the usual wrench. Any vibration tending to cause cap screw 10 to unthread from element 83, that is, anyrotation in the direction of the arrow J of Figure 19, will only result in causing the in-' clined surface I4 of the cap screw to move be--v neath the inclined nose 19 0f the member 18. The bodily resiliency of the member I8 urging it to oversized relation and thus into firmcontact will furthermore prohibit such, rotation of the cap screw since this characteristic of the member I8 will prevent it from moving with respect to the threads 82. It will thus be seen that the invention of Figures 16 to 21 comprises a permanent lock against the removal of a cap screw or other threaded element with respect to a companion threaded element.

Figure 20 is a ship between the cap screw 10 and floating threaded member 18, threaded member 83, showing In this position development of the relationnose I9 are bevelled on each I the relation of these parts when the nose [9 has a to the cap'screw shown the position with respect from Figure 20 in Figure 19. It will be clear that the undersurface 80 of the nose I9 bears upon theincline 14 of the cap screw while the 13 the member Qinvention shown in Figures outer surface 86 of the nose bears upon the root of the thread 62 so that movement of the cap screw to the right in Figure 20 is entirely prohibited.

The forms of the invention shown in Figures 1 to 15 result in a strong outward pressure being exerted upon a female thread by the portion of the member 25 which is of oversize diameter with respect to the female threads, viz., the portion of member 25 within approximately 225 of trailing end 36. On the other ,hand,'because at least the major portion of the remainder of the member 25 has an outside diameter less than the greatest diameter of the female thread, this portion may bend progressivelyto permit nose 29 to move upon surface 2| of restriction and into groove 6 when strong unthreading force is applied through a wrench.

, It will be understood that in the form of Figure 25a will have greater resistance to unthreading because of the pressure exerted axially or laterally upon the threads of acompanion threaded element by the resiliency of the offsets 86 and 62.

. The form of Figures 16 to 21 is constructed with substantially the same proportions as the forms of Figures 1 to 15 except that it omits the bent-in nose portion 29. That is, it is necessary that the form of Figures 16 to 21 be suf- ,ficiently oversize'throughout such portion of its length that it cannot have unthreading movement when screw 10 is turned in an unthreading direction. I

It will be understood that in the forms of the 1 to 15, theinwardly bent nose of the floating thread members 25 and 25a comprise enlargements, and that the re striction 26 on the carrierelements I is likewise an enlargement which enlargements on the floating thread members to force the latter into extremely close contact with the companionv elements is threaded. Obviously, sure is exerted upon the companion threaded element by the members 25 and 25a when the surface 2| of restriction 20 is beneath the nose of a member 25 or 25a. This is due to the fact that atthis'time floating thread memberis strongly urged against the companion threaded elemen The inwardly bent ends 29 of the members 25 and 25a and the restrictions 20 which cooperate therewith moved except by special tools.

It will be clear that the invention is applicable to threaded elements of numerous types other than cap screws. 1

The terminology used in the specification is for the purposeof description, the scope of the invention' being indicated in the claims.

' 1. In a self-locking threaded device, an element including a helical groove having a pitch substantially corresponding to the pitch of its threads, a

will cooperate with the in which the element I maximum zradial presthe maximum length of the likewise comprise coacting cam surfaces. The inclined end of the member I8 of Figures 16 to 21 and the cooperating substantially helical" member mounted in thegroove', at least a portion of said member nor-- mally" being of a different radius from the radius.

of the thread of said element, said helical mornher being bodily resilient tob'end andthereby conform .to an companion threaded" element engaged by' said first element, but being sufficiently rigid that it will exert radial pressure upon the compani'on element to" resist turning movement with respect to thelatter, and coacting, means carried by said threaded element andsaid helical member whereby the latter will be more strongly urged into contact with a companion threaded element upon unthreading movement of'said first thread ed element with respect t'o'a companion threaded element.

2. In a self-locking threaded device, an element including a helical groove having'a pitch'subst'am tially corresponding to the pitch of' its threads,

the groove having a. restriction therein, a suba stantially helical member mounted in the groove,- at least a portion of said member normally being ofa different radius from the-radiusofthetliread of said element, saidhelical member being bodily resilient to bend and thereby conform to acompanion threaded element engaged by said first element, but being sufficiently rigid that it will exert radical pressure upon' the companion element to resist turning movement with respectto the latter, said groove restriction being adapted to engage said memberupon unthreading ofsaid first element with respect to acompanionthread ed element. l

3:. In a self-locking threaded devicaan element including" a helical groove having a pitch substam tially corresponding to the pitch or its threads", the groove" having a restriction therein, a sub' stantially helical member mounted in the groove, at least?) portion of saidiner iiber normally being of'greater radius than the radius of the thread of saidelement, said member being bodily resil' ient so that it will bend to conform to adorn-- panioh threaded element enga ed by said first element, but beifig-sufficientl'yi rigid that it; Will exert radial pressure upon the companion element to strongly resistturni'rig: movement with respect to the latter,- said groove restriction bein adapted to engage said member upon imthreading of said first element with respect to a' com panion threaded element.

4. In a self -lo ckirig threaded device, an element including a helical groove having: a pitch sub stantially corresponding to the pitch: of its threads, the grooveliaviiigl'a restriction therein; a substantially helical member mounted? in thegroove; said member including a portion bent-out of the helix, said groove restriction being adapted to engage said bentportion upon unthreading: of said element with respect to a. companionthread: ed element.

5. In a self-lockingthredded device, an element including a helical groove having a pitch sub-- stantially corresponding to thepitch of. its; threads, the groovehaving; arestriction therein, a substantially helical member mounted inthegroove, at least portions ofv said member nor:- mally being of greater radius than the radiusbodily resilient so that it will conform to a cornpanion' threaded element engaged by saidfirst element, but, when within a companion element, will exert sufficient pressure upon the latter as to prevent it from being; moved with respect to thecompanion element,.saidhelical member being bent inwardly at one "end thereof. and said groove having a restriction opposite said en of' said member to contactwithsaid bent end when the grooved element turns in an unthreadihg direc tion relative to a companion threaded element.

6. In a self-locking threaded device, anelement provided with a helical groove having a pitch substantially corresponding to the pitch of its threads; the groove having a restriction therein, a substantially helical member of less length than the groove and mounted in the groove for movement lengthwise of the latter, said member having'a portion thereof bent from a helix and adapted to have locking contact with the groove restriction upon unthreading movement of said threaded element with respect to a companion threaded element.

7'. In a self-lockingthreaded device, an elementprovided with a helical groove having a pitch substantially corresponding to the pitch of its threads, the groove having a restriction therein,,a substantially helical member of less length than the. groove and mounted in the groove for movement lengthwise of'the: latter, said member an'dlgroove havingoppositely' facing enlargements of the thread of said element, said member being thereon adapted to come into engagementupon unthreading movement of said threaded elements.

8. In a'self l'ockin-g threaded device, an element including a helical groove having a pitch substantially corresponding to the pitch of its threads, the groove having" an outwardlyprojecting, restriction therein, a substantially helical member mounted in the groove, said 'member" having aninwardly deflected portion on its lead ing end adapted to engage the restriction upon unthreading of said element, with respect to a companion threaded element;

9. In a self-locking threaded device, an element includinga helical groove having a pitch substantially corresponding to the pitch of its threads, the trailingend of said grooveterminating ina substantially radially extending shoulder, a radial projection adjacent the, leading and of said groove, a helical. member mounted in thegroove andof less length than the latter, said member including a portion adapted to engage the groove projection upon unthreading movement of the threaded element with respect to a companionthr'eaded element.

10. Inaself-locking threaded device, an element including a helical groove having a pitch substantially corresponding to the pitch of its threads, the trailing end of the groove terminating in a substantially radially extendings houlder, a radical projection adjacent the leading end of said groove, a helicalmember mounted in said grooveand of a length less than the length of the groove, said member having one end thereof adapted to engage the projection upon unthreading of said element with respect to a companion threaded element, so. that said end of the memher will be'forced against the companion threaded. element.

11. In a. self-locking, threaded device, an element including a helical groove. having a pitch substantially corresponding to the pitch. of its threads, the trailing end of said groove terminate ing in. a substantially radially extending, shoulder, a radial projection; adjacent the leadingvend of said groove, a substantially helical member mounted in said groove and of a. length subs stantially corresponding to. the length of vthe.

groove contained between its trailing end and said restriction, said projection beingv adapted. to

move beneath said member upon, unth-reading to a companion threaded element.

movement of said threaded element with respect 12. In a self-locking threaded substantially corresponding to the pitch of its threads, the groove having a restriction therein,

a substantiall helical member mounted in the groove, said memberextending through approximately 335 and having an outside radius throughout substantially 180 which is greater than the greatestjopposed diameter of ,a compamon threaded element so that said member.

will not turn with respect to a companion threaded element upon vibration, and cooperating means in the groove'and upon the remaining portion of the length of said member adapted to engage and further urge said member into looking relation with a companion threaded element upon unthreading movement of said grooved elementwith respect to the companion threaded element.

13. In a self-locking threaded device, an element including a helical groove having a pitch substantially corresponding to the pitch of its threads, the groove having a restriction therein, a substantially helical member mounted in the groove, said member extending through approximately 335 and having an .outside radius throughout substantially 180" which is greater than the greatest opposed radius of a companion threaded element, the remainder of the length of saidmember having a radius less than the greatest opposed diameter of a companion threaded element, and coacting-enlargements on the last mentioned portion of said member and in the groove adapted to come into contact upon unthreading movement of said threaded element with respect to a companion threaded element to urge said portion of small radius into contact with the companion element.

14. In a self-locking threaded device, an element provided with a helical groove having a pitch substantially corresponding to the pitch of its threads, the groove having a restriction therein, a substantially helical member mounted in the groove, said member including axially ofiset portions, and coacting means inthe groove and on said member adapted to come into contact upon unthreading movement of said threadedelement with respect to a companion threaded element to urge said member into engagement with the companion element.

15. In a self-locking threaded device, an element provided with a helical groove having a pitch substantially corresponding to the pitch of itsthreads, the groove having a restriction therein, a substantially helical member mounted in the groove, said member including axially offset portions positioned at substantially diametrically opposed points thereon, said offsets facing in opposite axial directions.

16. In a self-locking threaded device, an element provided with a helical groove having a pitch substantially corresponding to the pitch of its threads, the groove having a restriction therein, a substantially helical member mounted in the groove, said member including axially offset portions-positioned at substantially diametrically opposed points thereonysaid offsets facing in opposite axial directions, one ofiset being adjacent the leading end of said member and having its convex wall facing the leading and of said threaded element.

17. In a self-locking threaded device, an ele-' ment provided with a helical groove having a device, an element including a helical-groove having a pitch of its threads, a substantially helical member mounted in. the groove, a restriction in the groove, said helical member having a portion of gradually decreasing radial thickness at one end thereof adapted to be engaged by the restriction upon 'unthreading movement of the threaded element with respect toa companion threaded element to thereby urge said member into engagement with the companion element.

18. In a self-locking threaded device, a screw having within its threads a helical groove of a pitch substantiallycorresponding to the pitch of its threads, a substantially helical member mounted in said groove, said helicalmember being of less length than the groove and being freelymovable lengthwise of the groove, said helical member having portions curved on radii of different'lengths, the radiusof curvature of'l' a portion of said member providing an'arc sub-' 1 stantially concentric in respect to the screw and than the groove and freely movable lengthwise the radius of curvature of another portion of said member providing an arc eccentric in respect to the screw.

19. In a self-locking threaded device,,a screw havingwithin its threads a helical groove of a pitch substantially corresponding to the pitch of its threads, the groove having a radial projection forming a restriction therein reducing the depth of the groove at one portion thereof, a substantially helical member mounted in said groove, said helical member being of .less length of the groove, said helical member having portions curved on radii of difierent lengths, the radius of curvature of a portion of said member providing an are substantially concentric in respect to the screw and the radius of curvature of another portion of said member providing an arc eccentric in respect to the screw.

20. In a self-locking threaded device, a screw having within its threads a helical groove of a pitch substantially corresponding to the pitch of its threads, the groove having a radial projection forming a restriction therein reducing the depth of the groove at one portion thereof, a substantially helical member mountedin said groove, said helical memberbeing of less length than the groove and being freely movable lengthwise of the groove, said member having a portion thereof projecting inwardly whereby to engage said groove restriction when the member moves, lengthwise of the groove, said helical member having portions curved on radii of different lengths, the radius of curvature of a portion of said member providing an arc substantially concentric in respect to the screw and the radius of curvature of another portion of said member providing an arc eccentric in respect to the screw.

21. In a self-locking threaded device, a screw having within its threads a, helical groove of a pitch substantially corresponding to the pitch of its threads, a substantially helical member mounted in said groove, said helical member be-. ing of less length than the groove and being freely movable lengthwise of the groove, said helical member having portions curved on radii of different lengths, the radius of curvature of a portion of said member providing an arc substantially concentric in respect to the screw and the radius of curvature of another portion of said member providing an arc eccentric in respect to the screw, and the 'outside diameter of an appreciable portion of said member being sumciently greater than the outside diameter of the threads of said screw to take'up allplay' approximately 335 and having an outside radius throughout substantially 180 which is normally greater than the greatest opposed diameter of a companion threaded element so that said member will not turn with respect to a companion threaded element upon vibration; thetrailing end of said member being'adapted to abut against the trailing end-of said groove during threading movement of said grooved element with'respect to a companion threaded element, said member being provided with an inwardly curved resilent portion at its leading end, the, restriction. in the groove being adapted to move beneath said inwardly curved portion upon unthreading movement with respect to a companion element to thereby force said end outwardly into closer engagement with the com,-

panion element, said end portion being adapted to move over the groove restriction upon the application of sufiicient force. to said grooved element whereby 'said inwardly curved portion will contact with the radial shoulder at the leading end of the groove to force said member to unthread with said grooved element.

HIRAM R. HARDING. 

